Influence of Beta-2-Adrenergic Receptor Gln27Glu Polymorphism on the Autonomic Heart Rate Modulation in Young Sedentary and Physically Active Women

Background: Studies have shown an interaction between the autonomic heart rate (HR) modulation and genetic polymorphisms. Nevertheless, it is yet unclear how a particular genetic polymorphism may determine a pattern of autonomic HR control, especially regarding the role of physical exercise. The objective was to investigate the influence of of Beta-2-Adrenergic (β2-AR) Gln27Glu polymorphisms and exercise on HRV of young Brazilian women. Methods: The group was selected as Sedentary Group (SG; n = 88) and physically Active Group (AG; n = 99). The β2-AR polymorphisms were analyzed using PCR-RFLP. The amplicons were subjected to electrophoresis on a 10% acrylamide gel and stained with ethidium bromide. The HR was registered in real time for 15 minutes, in the supine-position. The heart rate variability (HRV) was analysed using Shannon’s entropy (SE), conditional entropy (complexity index [CInd] and normalized CInd [NCI]), and symbolic analysis (0V%, 1V%, 2LV%, and 2ULV%). Statistical analysis: Analysis of variance (ANOVA) with Fisher's Least. Results: AG presented higher values for SE and 2ULV%, and lower values for 0V% when compared to SG (p<0.05). There was no significant difference of any index among genotypes both from the complexity and symbolic analysis. The interaction between genotype and exercise did not significantly affect HRV. Conclusion: These results do not support the concept that the β2-AR Gln27Glu polymorphisms affects the HRV indexes in physically active or sedentary women.